This application is based upon and claims the benefit of priority of Japanese Patent Application No. H.11-21435 filed on Jan. 29, 1999, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a structure for fixing a grommet into a motor housing, in particular, a structure for fixing the grommet for waterproof sealing into a connector portion of the motor housing with which a connector of a wire harness is coupled, and a motor unit having the same structure and applicable to a power window regulator for vehicles.
2. Description of Related Art
A conventional power window regulator for opening/closing a vehicle door glass is composed of a motor unit and a regulator (a link mechanism). The motor unit is provided with a resin molding housing, a DC motor fixed to the housing, reduction gears housed in the housing, a wire harness with a connector coupled with a connector portion of the housing for current supply to the DC motor and a grommet fitted into the connector portion of the housing for waterproof sealing. The motor unit has a waterproof construction for its electrical circuit protection, since water running along the surface of the door window is likely to be entered into the motor unit.
As shown in FIGS. 9 and 10, the connector portion 52 of the housing 51 is formed in a column shape and the grommet 53 made of elastic rubber is formed in a tubular shape. For preventing water from entering into a coupling gap between the connector of wire harness and the connector portion 52, the grommet 53 is fitted closely into an outside circumferential surface of the connector portion 52.
To rigidly fix the grommet 53 to the connector portion 52, there have been contemplated various ways that, for example, an inside circumferential surface of the grommet 53 and an outside circumferential surface of the connector portion 52 are glued, the grommet 53 is fastened tight from outside by fasteners such as a C-ring and a clip cord to the connector portion 52 after the grommet 53 is put on the connector portion 52, a flange provided at a lower end of the grommet 53 is fastened by screws to a flange provided at a lower end of the connector portion 52 or an inwardly projecting portion of the grommet 53 is fitted into a groove or an undercut provided at a lower portion of the connector portion 52.
However, these ways have such problems that not only more number of component parts or more complicated manufacturing processes are required but also reliability for fixing the grommet 53 to the connector portion 52 is not always sufficient, in particular, in case that these fixing means can not be provided all around circumferences of the connector portion 52 because of a restricted shape of the connector portion 52 integrally provided with the housing 51.
Further, to cope with the problems mentioned above, it has been proposed that, as shown in FIGS. 9, 10 and 11, the connector portion 52 is provided at a lower outside circumferential surface thereof with a plurality of locking claws 54, to which a plurality of resilient locking pieces 55 provided at a lower end of the grommet 53 are respectively latched and fixed. Though this construction improves the fixing reliability, the manufacturing processes for fixing the grommet 53 to the connector portion 52 are still complicated and not suitable for automatic assembly thereof, since, after the grommet 53 is put on the connector portion 52, each of the resilient locking pieces 55 has to be pulled in a lower direction so that the locking pieces 55 may be once deformed resiliently in order to be engaged with each of the locking claws 54 and, then, resiliently returned to the original positions thereof.
Furthermore, as shown in FIG. 11, the connector portion 52 is provided at an inside thereof with a locking concave 56 with which a locking convex C1 of the connector C of the wire harness W is engaged for preventing the connector C from easily being left out the connector portion 52.
It is very difficult to form the locking concave 56 at the inside of the connector portion 52 simultaneously when the housing 51 is molded or formed in view of the molding die construction of the connector portion 52. Therefore, to form the locking concave 56, a locking member 57 provided primarily with the locking concave 56 is separately provided as shown in FIG. 12 and, when the housing 51 is molded, the locking member 57 thus separately provided is inserted into the molding die at a position corresponding to the inside of the connector portion 52 as shown in FIG. 11. The locking member 57 also has a plurality of grooves 59 for positioning a plurality of terminals 58 to be also inserted into the molding die when the housing 51 is molded.
The structure mentioned above, however, has a drawback that the locking member 57 is needed as an additional component part and the terminals 58 have to be primarily mounted on the locking member 57 before the locking member 57 is inserted into the die for molding. As a result, a higher manufacturing cost is required, compared with a case that only the terminals 58 are directly inserted into the die for molding.
The present invention has been made in view of the above mentioned problem, and an object of the present invention is to provide a waterproof sealing structure for easily fixing a grommet to a connector portion with which a wire harness connector is coupled with higher fixing reliability, least number of component parts and/or lower manufacturing cost.
It is an another object to provide a motor unit having the same structure as mentioned above.
To achieve the above object, the structure is composed of a housing provided with a connector portion formed at least partly in a column shape, a wire harness connector coupled with the connector portion with a coupling gap and a tubular shaped grommet made of resilient material put on an outside circumferential surface of the connector portion to waterproof seal the coupling gap. A plurality of locking convex portions are provided respectively with an interval therebetween around the outside circumferential surface of the connector portion. On the other hand, a plurality of concave portions are provided respectively with an interval therebetween around an inside circumferential surface of the grommet. By simply pushing the grommet to put on the connector portion, the grommet is resiliently deformed outwardly at the plurality of the convex portions and, after the grommet passes through the plurality of the convex portions, the grommet outwardly deformed is resiliently returned substantially to an original shape thereof so that the plurality of the concave portions may be engaged respectively with the convex portions to rigidly fix the grommet to the connector portion.
It is preferable that each of the concave portions is a through-hole penetrating radially through the grommet from an inside surface to an outside surface thereof.
Further, in case that the housing is provided with a base unit and a bridging portion connecting the base unit and a part of the circumferential surface of the connector portion, the convex portions are arranged except the outside circumferential surface of the connector portion axially extending from the bridging portion and the grommet is provided with a cut in order not to interfere with the bridging portion when the grommet is put on the connector portion and the concave portions are arranged except the circumferential surface of the grommet axially extending from the cut. In this case, it is preferable that at least a part of the outside circumferential surface of the grommet axially extending from the cut comes in contact with and is inwardly pressed against a surface of the base unit when the grommet is put on the connector portion. As a result, the circumferential surface of the grommet may be rigidly fixed in almost all ranges around the circumferential surface of the connector portion.
Preferably, the grommet is further provided with one or more projections on the outside circumferential surface of the grommet axially extending from the cut. Therefore, the outside circumferential surface of the grommet axially extending from the cut is inwardly pressed through the projections against the surface of the base unit. The projections serve to reduce a friction with the surface of the base unit when the grommet is pushed so as to be put on the connector portion.
Furthermore, it is preferable that a plurality of annular sealing lips are provided at the inside circumferential surface of the grommet. The sealing lips are resiliently deformed to come closely in contact with the outer circumferential surface of the connector portion so that waterproof function may be much more enhanced.
Further, the connector portion is provided with an annular positioning portion and a connector fitting portion axially extending from the annular positioning portion. On the other hand, the grommet is provided with a grommet fitting portion, a guide portion, and a taper shaped annular step portion on an inside thereof and on a boundary between the grommet fitting portion and the guide portion. An inside diameter of the guide portion is slightly larger than an outside diameter of the connector fitting portion. An inside diameter of the fitting portion is slightly smaller than an outside diameter of the connector fitting portion. Therefore, when the grommet is placed at first on the connector portion, the annular step portion is easily positioned, with a help of the guide portion, on the annular positioning portion to align in axial direction the grommet with the connector portion. When the grommet is pushed to the connector portion, the grommet fitting portion is fitted into the connector fitting portion by being resiliently deformed outwardly without disturbing the axial alignment.
The annular positioning portion may be formed in an inclined direction relative to an axis of the connector portion to avoid the interference with the bridging portion. In this case, the annular step portion is also inclined to correspond to the shape of the annular positioning portion.
In case that both of the annular step portion and the annular positioning portion are formed obliquely, it becomes easier to align in axial and angular directions the grommet with the connector portion before the grommet is pushed toward the connector portion for assembly.
It is preferable that the convex portions are arranged on the connector fitting portion and the concave portions are arranged on the guide portion. With the construction above, the concave portions may be engaged respectively with the convex portions simultaneously when the grommet is pushed so as to make the grommet fitting portion fit into the connector fitting portion.
Further, preferably, the sealing lips are arranged on the inside circumferential surface of the grommet fitting portion in parallel with the annular step portion. Therefore, in case that the annular step portion is inclined relative to the axis of the grommet or the connector portion as mentioned above, the sealing lips are also inclined relative to the axis of the grommet or the connector portion so that the grommet fitting portion may be fitted into the connector fitting portion with the least axial travel distance when the grommet is pushed to the connector portion for assembly.
Furthermore, preferably, the connector portion is provided with a locking hole penetrating therethrough perpendicular to the axis of the connector portion and the wire harness connector is provided with a locking convex portion to be engaged with the locking hole for preventing the wire harness connector from being left easily out of the connector portion. An outside of the locking hole is covered with the grommet. It is more preferable that the locking hole is formed to penetrate a circumferential wall of the connector portion on a side opposite to the connector fitting portion with respect to the annular positioning portion. As a result, the penetrating locking hole may be sufficiently sealed without adversely affecting the fitting of the grommet into the connector portion. In case that the annular sealing lips are provided obliquely as mentioned above, there is a sufficient space where the penetrating locking hole may be formed without prolonging the height of the connector portion for securing waterproof sealing.